This invention relates to realization of a multi-function portable wireless device. Some embodiments have an extremely low profile (meaning the thickness is a small fraction of width or height of the device). In some embodiments, the device is powered by multiple types of energy sources and energy storing methods. (An energy source can be solar power, vibration energy harvesting, Peltier thermo-electric array, dry cell, and/or some other source; rechargeable energy storage may include a rechargeable battery and/or super capacitor and/or some other type).
Some embodiments relate to long battery endurance electronic devices, wireless communication systems, RFID and tracking systems. Some embodiments are suitable for systems with devices where one or more of them are mobile.
A Ukey device available from SecureALL Corporation of California has been in use for the last few years, and has many breakthrough technologies that enable a hand-free key to provide door access. Namely the extremely long battery life due to ELP (extreme-low-power) technology, omni-directional (isotropic) antenna, low energy intensive cryptography (see US Pre-Grant Patent Publication 2012/0170751, incorporated herein by reference) and communication protocol (see US Pre-Grant Patent Publication 2013/0247153, incorporated herein by reference), which enable Access control information communication, efficient information synchronization etc.
Using the ELP energy conservation techniques (U.S. pre-grant patent publication no. US 2010/0040120, incorporated herein by reference), the omni-directional antenna (reliable RF link budget, US pre-grant patent publication no. US 20120169543, incorporated herein by reference), energy conserving communication can be achieved that allows a battery to operate for longer duration and/or more energy consuming functionality be added to the device. The present document discloses additional multiple new functions and innovative design elements in a future UKey, active RFID tag and sensor node; the disclosure can as well be applied to other appliances that require operating under limited energy and power constraints.
This document discloses methods to further increase battery life of an exemplary embodiment shown below as Ekey 240 (using CR2450 cell) from currently 4.5 years by a few times, or eliminate the need for a battery altogether. It also discloses methods to change the form factor to make it very thin (of the order of the thickness of current RFID access cards).
Conventional passive RFID technology suffers from an extremely short communication range (typically 5-30 cm) with an RFID reader, and its RFID readers requires very high operating power requiring main power operation or large batteries. It has low data rate and small data payload.
Prior art semi-active RFID tags technology requires a battery, and communicates over a longer range (typically 1-30 m) compared to passive RFID tags. The onboard battery is used only to provide power for telemetry and backscatter enabling circuits on the tag, not to generate RF energy directly. These systems have a low data rate and small-medium data payload. The RFID reader can be as power hungry as passive RFID reader.
The prior art active RFID systems have comparatively longer operating range (10-80 m) but require larger batteries for a reasonable battery change frequency. They provide high data rates and support larger data payloads. Its RFID reader is much less power hungry compared to passive RFID reader. Exemplary active-RFID products are available from AeroScout, WhereNet and PanGo.
Due to battery and antenna considerations the conventional active RFID devices have a rather tall profile that makes it uncomfortable to carry them in a pocket or wallet. There is a user demand for low profile electronic devices that can easily be carried in a pocket or a wallet. The present disclosure teaches methods to realize low profile electronic devices/appliances (appliances that are smart, multi-functional and that require no battery replacement). In some embodiments the battery is sealed in the case, or the device may not even have a primary battery (non-rechargeable battery).
A related problem in access control, people tracking and asset tracking is to be able to locate the relative position of the active electronic device in a cost effective way. Prior art technologies exist but they have the following significant disadvantages:                1. Direction Triangulation: Requires the space to be covered by two or more readers with direction finding capability.        2. Distance triangulation: Requires readers that can measure distance with the tag (time of flight measurement) and the desired space to be covered by two or more readers.        
An embodiment of this disclosure teaches the combined use of Time of flight (to get distance estimate) and a steerable beam (get directional estimate) to estimate the location of the tag. This method is much more cost effective as a standalone reader can provide positioning without requiring complex cabling or communication between multiple readers.
Some embodiments provide a multi-function Ekey 240 that is planar and low-profile like conventional passive RFID cards: the size of about a credit card and about 1 to 4 mm thickness. A preferred embodiment is about 60'30×2.5 mm.
SecureALL's customers love Ekeys (Model-UKN), the current product functionality and form factor; however, some users want it in a format like an employee badge that can be imprinted with a photo and other information. Such a form factor finds easy user acceptance because most already wear their employee badge (a pouch contains the employee badge, along with RFID proximity card in a transparent plastic pouch that has a clip attached to attach to a person's dress). After work they put the card in the wallet or along the wallet in their pockets. This disclosure teaches methods to use energy harvesting methods that significantly increase battery life exploiting the way the users typically use the Ekey at work and off-work.